Embodiments of the present invention relate to an optical element of a liquid crystal display, a liquid crystal display and a manufacture method thereof.
With rapid development of liquid crystal displays (LCDs) and increasing requirements on energy efficiency, light emitting diodes (LEDs) have gradually replaced cold cathode fluorescent lamp (CCFL) as the light sources for a backlight of a LCD. The LCD employing LEDs as light sources of the backlight has characteristics of low energy consumption and long life period and also is environment-friendly. At present, three primary color (i.e., RGB) LEDs or white LEDs are mainly used for manufacturing a backlight. The backlight having three primary color LEDs has a higher cost in comparison with that having white LEDs. In addition, among various kinds of white LEDs, the white LEDs in each of which white light is obtained by mixing blue light from a blue LED and yellow light by exciting yellow fluorescence powders with blue light from the blue LED are most widely used. The blue LED and the yellow fluorescence powders are encapsulated in one package to form one white LED. In the spectrum of the white light obtained in the manner described above, the intensity of red light component is relatively weaker.
In a LCD, the light coming from the light source(s) of a backlight is transmitted to a color filter substrate through optical elements such as a light guide plate, a diffusion film, a prism film, a lower polarization plate, and the like. FIG. 1 shows a spectrum of the LCD that employs white LEDs, in each which white light is obtained by mixing blue light and yellow light by exciting yellow fluorescent powders with blue light, as a backlight. In FIG. 1, the wavelength range of the red light component is about 640˜780 nm, the wavelength range of the green light component is about 505˜525 nm, and the wavelength range of the blue light component is about 470˜505 nm. As shown in FIG. 1, the red light component in the excited white light is insufficient after the white light passes through the backlight, because the intensity of the red light component in the white light obtained by exciting yellow fluorescent powders with blue light is relatively weaker as described above. Therefore, color shift occurs for the images displayed by the LCD with the light from the backlight.